You have to try and stick to the light cycle.
The plants flower because of the extended dark hours. (12)
They build up their hormone levels during dark.
If you decrease that for several days in a row, the flower stage gets interrupted big time and most likely will get you craps for smoke.
The amount of light for the 12 hours cycle can be neglected for a few days, as long as its light, and the plant can react to that.
If you are able to move the plant about twice a day for the duration I would go with that.
I would simply place it for 12 hours in the room with the MH light, and take it out after 12 hours, and place it in the dark room for 12 hours.
Its a bit of work, but far more likely to produce a decent smoke.